Air-pump.



No. 756,630. PATEENTED APR. 5, 1904. J. s. HBMBNWAY.

AIR PUMP.

APPLICATION FILED JUNE 12. 1903.

/ I 7 al llforqeys UNTTED STATES Patented April 5, 1904.

PATENT OFFICE.

. AIR-PUMP.

SPECIFICATION forming part of Letters Patent No- 756,630, dated April 5,1904.

Application filed Tune 12, 1903.

To all whom it may concern:

Be it known that I, JUSTIN SAMUEL HEMEN- WAY, a citizen of the UnitedStates, residing at River Falls, in the county of Pierce and State ofWisconsin, have invented a new and useful Air-Pump, of which thefollowing is a specification.

This invention relates to air-pumps.

The principal object of the invention is to provide an air-pump ofsimple and durable.

construction by means of which an .almost perfect vacuum may be readilyproduced and maintained as long as may be desired.

Another object of the invention is to produce an air-pump in which novalve need be opened to permit the passage of air from the receiver orbell into the cylinder.

A further object of the invention is to provide an air-pump with partsso designed that the piston need not fit closely within the barrel ofthe cylinder.

A further object of the invention is to provide in an air-pump animproved form of valve at the end of each cylinder and a-liquid seal inconnection with the valves to prevent the return of air to the cylinderafter having once been forced out.

With the objects above stated and others in view, which will appear asthe invention is more fully disclosed, the same consists in theconstruction and novel combination and arrangement of parts of anair-pump hereinafter described, illustrated in the accompanyingdrawings, forming part of this specification, in which correspondingparts are designated by the same characters of reference in the severalviews in which they appear, and having the novel features thereofspecifically pointed out in the appended claims.

In the drawings, Figure 1 is a View in longitudinal median sectionthrough the pump structure above the base and with portions of the basebroken away to show the mode of attaching the superstructure thereto.Fig. 2 is a detail view in perspective of one end of the pump, showingthe pressure-gage attached thereto.

Referringto the drawings by reference characters, ldesignates a base,whichmay be of Serial No. 161,246. (No model.)

any suitable form and which will preferably be made of wood. Near eachend of the base is provided a hollow standard-tube 2, attached to thebase in any suitable manner. Extending between the tubes 2, near thebottom thereof, is the cylinder 3 of the air-pump, which is open at eachend for reasons that will afterward appear. In alinement with thecylinder and projecting out from the side of each standard-tube 2 isatubular extension 4:. One of the extensions 4. is closed by ascrew-plug 5, having a knurled or milled head and fitting tightly intothe end of said extension. The other extension carries in the endthereof a stufiing-box 6, extending through which is a piston-rod 7,having at the outer end a handle 8 of suitable form and at the inner enda piston-head 9 of substantially cylindrical form, but provided on thesurface thereof with a plurality of cir-' cumferential grooves 10, theutility of which will hereinafter appear. In the extension closed by theplug 5 is a valve 11, comprising a disk 12, a solid stem l3,wl1ich isrigidly secured to the disk, and a spring 14. The stem 13 is slidablymounted in the extension 1 of the cylinder, and the disk 12 is ground tofit smoothly against the adjacent end of the cylinder, in contact withwhich it is normally held by means of the spring 14:, which encirclesthe stem 13 and abuts at one end against the extension i and at theother end against the disk 12. In the other extension 4 of the cylinderthere is. mounted a valve 15, comprising a disk 16, ahollow stem 17,through which passes the piston-rod 7, and a spring 18. The spring 18abuts at one end against the extension 4 and at the other end againstthe disk 16, serving to keep the disk normally in contact with the endof the cylinder, which is ground to form perfect contact with said disk.The cylinder has a small opening 19 in the upper surface thereof aboutmidway between the ends, and extending upward from the cylinder aboutmidway between the ends, where it encircles the opening 19, is atube'20, disposedat right angles to the cylinder and havingat the up perend thereof avalve 21 and a disk 22, provided with a central opening forthe passage of air and adapted to support a bell-glass or other suitablevessel to form an exhaustchamber. Extending through the tube 20. buthaving no communication with the interior thereof, are two transversetubes 24 and 25, the ends of which open into the standardtubes 2.

At the top of one of the standard-tubes 2 is preferably provided apressure-gage 26, and at the top of the other standard-tube 2 ispreferably provided an extension 27, having a stopcock 28, which may beclosed to prevent the ingress or egress of air at any time.

When the pump is to be put into use, oil is poured into one of thestandard-tubes 2 until it rises above the level of the transverse tubeThis oil serves to keep all the working parts lubricated and also formsa liquid seal around each of the valves provided at the ends of thecylinder, thus making their action entirely certain and preventing thereturn of air to the cylinder.

In using the air-pump as an exhaust-pump the procedure is-similar tothat ordinarily employed in air-pumps. The vessel to be exhausted of itscontents is placed with its mouth in contact with the disk 22 and sothat the mouth thereof may be over the opening 19. Oil having beenintroduced into the standardtubes in sufficient quantity and the marginof the vessel to be exhausted having been brought into suitable contactwith the surface of the disk 22, the piston-rod 8 is rapidlyreciprocated within the cylinder. As each stroke of the piston leaves avacuum behind it, air is drawn down tube 20 through the opening 19 intothe cylinder to fill the space behind the piston, and on each returnmovement a portion 'of the air returns to the receiver and a portion ofit is carried out by the piston-head. During the first'half of a strokeof the piston in either direction there is no tendency for air to passdownward into the cylinder, because the air remaining in the cylinder iscompressed thereby; but after the piston-head passes the opening in thecylinder which communicates with the interior of tube 20 air is drawndownward from the receiver to fill the space behind the piston, and theair imprisoned between the piston and the valve at the end of thecylinder which the piston is approaching is of necessity carried forwardby the piston and is forced through the valve and allowed to escape intoone of the standard-tubes.

When the pump is used as a compressionpump, a suitable vessel to receivethe com- I pressed air may be attached to the end of the "fxtension 27,or the valve 28 may be closed and the air compressed in the space in theupper part of the standard-tubes 2. In either case the action of thepump is substantially the same as that already described in explainingthe use of the pump as an exhaust-pump.

The piston is reciprocated in exactly the same manner and air is drawndown from the tube the piston, which at each stroke forces a certainquantity of air through one of the valves at the end of the cylinderinto one of the standardtubes 2. As the upper parts of the standardtubes2 are connected by apipe 24:, the pressure of the air in eachstandard-tube will always be exactly equal to that in the other, so thatthe pressure-gage 26 will indicate the degree of compression of the airin both of the standard- .tubes 2, and in case a vessel is attached tothe extension 27 the compression of the air in the vessel will also beindicated by the pressure-gage 26. As each of the valves at the end ofthe cylinder is completely covered by oil or some other suitable liquid,it is obvious that no air can return from the standard-tubes into thecylinder, but will at once pass upward through the oil or other liquidto the surface thereof when forced through either of the valves. Thecircumferential grooves 10 on the piston-head 9 are filled with oil atthe end of each movement of the piston, and being so filled as thepiston recedes and the valve closes behind it the oil in the grooves inthe piston-head fills the space between the sides of the piston-head andthe wall of the cylinder, forming an air-tight joint and making the useof any packing on the piston-head unnecessary. The action of the oil informing an air-tight joint between the piston-head and the cylinder-wallis so effectivethat the piston-head may be preferably smaller indiameter than the interior of the cylinder, and thus be caused toreciprocate more readily within the cylinder than in air-pumps ofdifferent type of construction in which the piston-head has to make atight fit withinthe cylinder. As all the valves of the cylinder arecompletely sealed with oil at all times, this oil may leak into thecylinder; but no air can pass in until enough oil has entered thecylinder to have the valves unsealed, and as the valves are air-tightthe pump will maintain whatever vacuum has been produced for anindefinite time.

Some of the special advantages possessed by this form of air-pump arethat as the valve covers the entire end of the cylinder it furnishes alarge opening for the escape of air when the valve is opened; second, itallows the end of the'piston to pass out of the cylinder into the oil,thus making it impossible for any air tobe left in the cylinder, and,third, the arrangement of the spring-pressed valves in alinement withthe bore of the cylinder provides at either end of the cylinder acushion for the piston to strike against as it comes to the end of astroke.

As all theworking parts of the pump are kept at all times in a quantityof clean oil, they are at all times in the same general condition andrepairs are extremely seldom required. As all the parts of the pump aremade of metal, they form an exceedingly durable structure and remainalways in. order.

Having thus described the construction and operation of my invention,What I claim as new, and desire to secure by Letters Patent,

1. The combination in an air-pump, of an open-ended cylinder having aninlet-opening intermediate of its ends, oil-receptacles within which theends of said cylinder are located, a pipe connecting saidoil-receptacles, valves within said oil-receptacles to keep the ends ofsaid cylinder normally closed, and a piston mounted for reciprocationwithin said cylinder.

2. The combination in an air-pump, of a cylinder having open ends andprovided with an inlet-opening intermediate of its ends, oilreceptacleswithin which the ends of said cylinder are located, a pipe connectingsaid oilreceptacles near the bottom, a second'pipe connecting saidoil-receptacles near the top, valves within said oil-receptacles to keepthe ends of said cylinder normally closed, and a piston mounted forreciprocation Within the cylinder.

3. The combination in an air-pump, of a cylinder having open ends and aninlet-opening intermediate of its ends, oil-receptacles Within which theends of the cylinder are located, tubular members fitted in the sides of&

said oil-receptacles opposite the ends of the piston, plugs closing theouter ends of said tubular members, springs seated in said tubularmembers, Valve-disks, having stems en circled by said springs, heldnormally in contact with the ends of said cylinder, and a piston mountedfor reciprocation within said cylinder.

4. The combination in an air-pump of a horizontallydisposed, openendedcylinder having intermediate of its ends an air-inlet opening, verticaloil-receptacles within which the ends of said cylinder are located,valves keeping the ends of said cylinder normally closed, a pistonmounted for reciprocation within said cylinder, pipes disposed parallelwith said cylinder and connecting said oil-receptacles near the bottomand near the top thereof, caps on said receptacles, andpressuremeasuring means associated with one of said receptacles.

In testimony that I claim the foregoing as my 'own I have hereto affixedmy signature in the presence of two witnesses.

' JUSTIN SAMUEL HEMENWAY.

itnesses:

OSCAR HEMM, FRED KNoBEL.

